The present invention relates to a side airbag apparatus that protects an occupant seated in a vehicle seat by deploying and inflating an airbag on a side of the occupant when an impact is applied to the vehicle from the side of the vehicle seat.
A side airbag apparatus is widely known as an apparatus that protects an occupant seated in an automobile seat when an impact is applied to the seat from a side, for example, due to a side collision. Such a side airbag apparatus includes an airbag main body forming the outer shape of the airbag and a gas generator arranged in the airbag main body. The airbag main body is folded into a storage form and stored in the seat back of an automobile seat together with the gas generator.
In the side airbag apparatus, when an impact is applied from the side to a member forming the side portion of the automobile (body side portion) such as a side door, inflation gas is supplied from the gas generator into the airbag main body so that the airbag main body is deployed and inflated. The airbag main body is projected from the automobile seat with a part remaining in the seat back. Thereafter, the airbag main body is deployed and inflated in a predetermined deployment region between the occupant and the body side portion. The airbag main body restrains the occupant and mitigates the impact that is transmitted from the side to the occupant through the body side portion.
One form of such a side airbag apparatus is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2008-87632. In this side airbag apparatus, the airbag main body is spread into a flat state without being supplied with inflation gas, that is, an uninflated-spread state, to be turned into a storage form. The airbag main body in this state is folded from the front end toward the rear end, so that the airbag main body has a stacked portion, which has a vertically elongated shape. The stacked portion includes a plurality of structural segments each extending vertically. The structural segments stacked onto each other in the thickness direction.
The stacked portion includes a first stacked section, which forms a lower part, and a second stacked section, which forms a part above the first stacked section and accommodates the gas generator. The first stacked section is folded back rearward to be arranged behind the second stacked section.
Thus, the airbag main body in the storage form is deployed and inflated in a manner different from the manner in which the first stacked section is arranged in front of the second stacked section.
That is, in the side airbag apparatus, in which the first stacked section is arranged in front of the second stacked section, inflation gas flows to the second stacked section and the first stacked section in that order. The first stacked section is pivoted forward about the boundary between the first stacked section and the second stacked section. At this time, the second stacked section being inflated pushes the first stacked section forward, thereby accelerating the forward pivoting motion of the first stacked section. With the pivoting motion of the first stacked section, the structural segments in the first stacked section are deployed and inflated forward with momentum to project forward beyond the predetermined deployment region. If an obstacle exists in the path of the deployment of the airbag main body, the lower part of the airbag main body may thrust upon the obstacle.
In contrast, in the side airbag apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-87632, the first stacked section is pivoted behind or below the second stacked section about the boundary between the first stacked section and the second stacked section. Even though the second stacked section is inflated, the first stacked section, which is located behind the second stacked portion, is not pushed forward. With the pivoting motion of the first stacked section, the structural segments in the first stacked section are first deployed and inflated behind or below the second stacked section. Subsequently, the structural segments in the first stacked section are deployed and inflated in front of the second stacked section. The structural segments in the first stacked section are prevented from being deployed and inflated forward with momentum and projecting forward beyond the deployment region. Thus, even if there is an obstacle in the deployment path of the airbag main body, the lower part of the airbag main body is restricted from thrusting upon the obstacle.
However, in the side airbag apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-87632, if an airbag main body with a great vertical dimension is used, the first stacked section in the stacked portion in the storage form is elongated. Thus, the long first stacked section is pivoted about the boundary between the first stacked section and the second stacked section. Accordingly, the structural segments in the first stacked section are deployed and inflated. Thus, during the process of forward deployment and inflation, the structural segments in the first stacked section can project forward beyond the deployment region. The effect of restricting the lower part of the airbag main body from thrusting upon the obstacle is thus unsatisfactory.
Particularly, the side airbag apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-87632 is configured such that the airbag main body is divided into at least an upper inflation chamber and a lower inflation chamber, and inflation gas is preferentially supplied to the lower inflation chamber. Regarding the stacked portion of the airbag main body, inflation gas is preferentially supplied to the first stacked section, which constitutes the lower part of the stacked portion. Thus, the structural segments in the first stacked section are likely to be deployed and inflated forward with momentum and project forward beyond the deployment region. Therefore, restriction of such forward projection of the structural segments in the first stacked section is effective in mitigating the impact applied to the obstacle.
The above described drawbacks are not limited to automobiles, but may be found in any type of vehicles equipped with a side airbag apparatus.